1/n * sum over d|n of {mu(n/d) * (4d)! / d!^4}.

A074652

1/n * sum over d|n of {mu(n/d) * (4d)! / d!^4}.

Terms

    a(0) =24a(1) =1248a(2) =123192a(3) =15765120a(4) =2346549000a(5) =384790520160

External references